title: Identification of a conserved JEV serocomplex B-cell epitope by screening a phage-display peptide library with a mAb generated against West Nile virus capsid protein.
abstract: BACKGROUND
  The West Nile virus (WNV) capsid (C) protein is one of the three viral structural proteins, encapsidates the viral RNA to form the nucleocapsid, and is necessary for nuclear and nucleolar localization. The antigenic sites on C protein that are targeted by humoral immune responses have not been studied thoroughly, and well-defined B-cell epitopes on the WNV C protein have not been reported.
  
  
  RESULTS
  In this study, we generated a WNV C protein-specific monoclonal antibody (mAb) and defined the linear epitope recognized by the mAb by screening a 12-mer peptide library using phage-display technology. The mAb, designated as 6D3, recognized the phages displaying a consensus motif consisting of the amino acid sequence KKPGGPG, which is identical to an amino acid sequence present in WNV C protein. Further fine mapping was conducted using truncated peptides expressed as MBP-fusion proteins. We found that the KKPGGPG motif is the minimal determinant of the linear epitope recognized by the mAb 6D3. Western blot (WB) analysis demonstrated that the KKPGGPG epitope could be recognized by antibodies contained in WNV- and Japanese encephalitis virus (JEV)-positive equine serum, but was not recognized by Dengue virus 1-4 (DENV1-4)-positive mice serum. Furthermore, we found that the epitope recognized by 6D3 is highly conserved among the JEV serocomplex of the Family Flaviviridae.
  
  
  CONCLUSIONS
  The KKPGGPG epitope is a JEV serocomplex-specific linear B-cell epitope recognized by the 6D3 mAb generated in this study. The 6D3 mAb may serve as a novel reagent in development of diagnostic tests for JEV serocomplex infection. Further, the identification of the B-cell epitope that is highly conserved among the JEV serocomplex may support the rationale design of vaccines against viruses of the JEV serocomplex.
authors.affiliation: The Key Laboratory of Veterinary Public Health, Ministry of Agriculture, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, PR China.
authors.forename: En-Cheng
authors.initials: EC
authors.lastname: Sun
authors.forename: Jing
authors.initials: J
authors.lastname: Zhao
authors.forename: Tao
authors.initials: T
authors.lastname: Yang
authors.forename: Ni-Hong
authors.initials: NH
authors.lastname: Liu
authors.forename: Hong-Wei
authors.initials: HW
authors.lastname: Geng
authors.forename: Yong-Li
authors.initials: YL
authors.lastname: Qin
authors.forename: Ling-Feng
authors.initials: LF
authors.lastname: Wang
authors.forename: Zhi-Gao
authors.initials: ZG
authors.lastname: Bu
authors.forename: Yin-Hui
authors.initials: YH
authors.lastname: Yang
authors.forename: Ross A
authors.initials: RA
authors.lastname: Lunt
authors.forename: Lin-Fa
authors.initials: LF
authors.lastname: Wang
authors.forename: Dong-Lai
authors.initials: DL
authors.lastname: Wu
mesh_terms: D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000032:analysis*; D036022:Capsid Proteins / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D017124:Conserved Sequence; D004664:Encephalitis Virus, Japanese / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D004672:Encephalitis, Japanese / Q000276:immunology / Q000821:virology; D018604:Epitope Mapping; D018985:Epitopes, B-Lymphocyte / Q000737:chemistry* / Q000235:genetics / Q000276:immunology; D006801:Humans; D008969:Molecular Sequence Data; D019151:Peptide Library; D016415:Sequence Alignment; D014901:West Nile Fever / Q000276:immunology / Q000821:virology; D014902:West Nile virus / Q000737:chemistry* / Q000235:genetics / Q000276:immunology
chemical_list: D000911:Antibodies, Monoclonal; D036022:Capsid Proteins; D018985:Epitopes, B-Lymphocyte; D019151:Peptide Library